The Natural Hormones website suggests that progesterone levels may fluctuate during the course of a woman's normal menstrual cycle, and low progesterone levels are common during the follicular phase of the menstrual cycle. Women with low progesterone levels may suffer from estrogen dominance. Psychological symptoms of low progesterone levels in women include anxiety, irritability and mood swings. Physical symptoms of low progesterone in women include headaches and premenstrual syndrome.
According to the Natural Hormones website, high stress levels may cause lower progesterone, and vice versa. A Christian Broadcasting Network article suggests that stress reduces progesterone, interfering with a woman's reproductive capacity, and is a leading cause of infertility and miscarriages. A woman's body requires progesterone to conceive--progesterone prepares the uterine lining for the fertilized egg. Progesterone is also responsible for feeding and nourishing the uterus throughout pregnancy. Stress triggers a woman's body to produce additional cortisol and adrenaline, effectively diminishing progesterone levels.
The Women Living Naturally website suggests that xenohormones may contribute to estrogen dominance and low progesterone. Xenohormones are man-made synthetic substances that have hormone-like effects. The Natural Hormones website suggests that exposure to synthetic substances, like plastics, may increase estrogen levels and stimulate a lower progesterone levels. Plastics contain xenohormones, which mimic estrogenic activity and create hormone imbalance. Pesticides, herbicides and fungicides that derive from petrochemicals may also contain xenohormones. Solvents and adhesives like fingernail polish and cleaning supplies may contain xenohormones, as well as automobile exhaust and PCBs.
Natural Hormones suggests that synthetic progestins can lower progesterone levels. According to the Project Aware website, synthetic hormones such as progestin and medroxyprogesterone can lower the amount of progesterone circulating in a woman's blood. The development of birth control pills coincides with the development of synthetic progestins. Most birth control pills contain a synthetic progestin. According to Natural Hormones, synthetic progestins can occupy and block progesterone receptors in a woman's body, which may cause progesterone deficiency. Progestins have some progesterone-like effects and may be up to 100 times more potent than natural progesterone. The Women Living Naturally website suggests that oral contraceptives and conventional hormone replacement therapy may contain synthetic estrogens and progestins that lower progesterone levels and contribute to estrogen dominance.